I’d guess they tightened the screw on the home button too loosely/tightly, although I’d have to see the phone to be sure. In any event, if it wasn’t that sensitive before and it became that oversensitive after the battery replacement, then they should absolutely be footing the repair costs (if any) for the home button. (Though based on the way they usually do things, you might have to fight them a bit on it to get them to cover it).

Looking at a basic specsheet, you should be able to upgrade RAM (just DDR3 SODIMMs) and HDD (a 2.5inch drive) without any issues, and possibly the DVD drive as well. Most likely, the CPU and GPU are nonupgradeable, as those components are usually soldered to the board in laptops.

Something I do that you might try is use sturdy playing cards to try getting under the corners of the back glass (using a sliding motion along the edge of the glass) once you’ve heated the back glass of the phone (either with the iOpener or with a hairdryer/heatgun). Once you get a tiny bit under the glass, you can insert more cards under the glass and the already inserted card, then slowly go around the phone and cut the adhesive holding the back on. The phone should be hot enough that you can just barely touch/hold it, in my experience - make sure the glass is very heated, as the adhesive on there is quite strong and can cause the glass to break if you put too much lifting pressure on the glass before getting through all the adhesive. If you do it right, you can even keep the original adhesive intact.

Do you have another phone you can test the battery in? If so, I’d try that to see if the battery itself is fine. It may be a dead battery, in which case you’d simply need to get a new battery.

Your LCD (display part of the screen) is broken in addition to the glass. You’ll need to replace the display assembly.

Maybe check how tightly you’re screwing in the center screw directly on the home button? Sometimes if that’s too tightly screwed in the home button will malfunction.

If it has a removable HDD/SSD, you can open it up and remove the drive, then read and copy the contents off on a different computer. What’s the model of the laptop?

I’d guess a broken LCD (display part of the screen). So you’d need to replace the display assembly.

A black line down the screen would likely indicate the LCD is broken, so you’d have to replace the LCD display itself. If glass is broken, you’ll want to replace that; if not, then don’t. If touch is still working, then the digitizer is not broken. I’m not familiar with that model, but depending on the tablet some devices have the entire LCD + digitizer + glass as one assembly, whereas some have the digitizer + glass separate from the LCD. If that tablet has a single display assembly, you’d need to replace the entire thing; if it has a separated assembly you could possibly get away with replacing just the LCD (assuming the glass isn’t broken).